Currently, modems employ audio/data transformers for coupling their circuitry to telephone lines. Such a transformer is often large and costly. In some applications, such as the currently-popular notebook computers, a bulky line transformer is highly undesirable. However, a line transformer affords large bandwidth performance which is necessary for modem operation.
It is therefore desirable to provide an alternative to the traditional line transformer without sacrificing frequency performance. Ideally, such a device would be smaller and less expensive to manufacture.